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Genetic variability of West Nile virus in US blood donors, 2002-2005.

Grinev A, Daniel S, Stramer S, Rossmann S, Caglioti S, Rios M - Emerging Infect. Dis. (2008)

Bottom Line: Complete genomic sequences of 8 isolates and structural gene sequences from 22 additional isolates were analyzed.We found some genetic diversity in isolates from different geographic regions and genetic divergence from reported sequences from epidemics in 1999-2001.Nucleotide divergence of structural genes showed a small increase from 2002 (0.18%) to 2005 (0.37%), suggesting absence of strong selective pressure and limited genetic evolution of WNV during that period.

View Article: PubMed Central - PubMed

Affiliation: Food and Drug Administration, Bethesda, Maryland, USA.

ABSTRACT
West Nile virus (WNV) was detected in the United States in 1999, has reoccurred every summer since, and has become endemic. Transfusion transmission was documented in 2002, and screening of blood donations for WNV began in 2003. We investigated genetic variation of WNV in human isolates obtained from specimens collected from 30 infected blood donors who tested positive for WNV RNA during 2002-2005. Complete genomic sequences of 8 isolates and structural gene sequences from 22 additional isolates were analyzed. We found some genetic diversity in isolates from different geographic regions and genetic divergence from reported sequences from epidemics in 1999-2001. Nucleotide divergence of structural genes showed a small increase from 2002 (0.18%) to 2005 (0.37%), suggesting absence of strong selective pressure and limited genetic evolution of WNV during that period. Nevertheless, WNV has continued to diverge from precursor isolates as geographic distribution of the virus has expanded.

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Phylogenetic tree of complete genomes of West Nile virus (WNV) isolates collected during the 1999–2005 epidemics in the United States. Phylogeny reconstruction was estimated by using MEGA version 3.1 (www.megasoftware.com) on the basis of maximum parsimony analysis. Solid circles indicate isolates from this study. Values near branches represent percentage support by parsimony bootstrap analysis. Some parsimony-informative positions (1442, 2446, 4146, 6138, 6721, 8811, 10408, and 10851) play an important role in topologic arrangement of the tree and outgroup configurations. The tree was rooted with prototype WNV isolate WN-NY99 (AF196835) and the most closely related Old World isolate, IS-98 (AF481864). Culex q., Culex. quinquefasciatus; Culex t., Cx. tarsalis; Culex p., Cx. pipiens. WNV genotype is color coded: green, WN99; blue, WN02.
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Figure 3: Phylogenetic tree of complete genomes of West Nile virus (WNV) isolates collected during the 1999–2005 epidemics in the United States. Phylogeny reconstruction was estimated by using MEGA version 3.1 (www.megasoftware.com) on the basis of maximum parsimony analysis. Solid circles indicate isolates from this study. Values near branches represent percentage support by parsimony bootstrap analysis. Some parsimony-informative positions (1442, 2446, 4146, 6138, 6721, 8811, 10408, and 10851) play an important role in topologic arrangement of the tree and outgroup configurations. The tree was rooted with prototype WNV isolate WN-NY99 (AF196835) and the most closely related Old World isolate, IS-98 (AF481864). Culex q., Culex. quinquefasciatus; Culex t., Cx. tarsalis; Culex p., Cx. pipiens. WNV genotype is color coded: green, WN99; blue, WN02.

Mentions: Phylogenetic analysis of complete genomes of WNV isolates provided stronger evidence of evolutionary relationships between isolates. Eight fully sequenced isolates were compared by phylogenetic analysis with 39 published complete WNV genomes present in the United States during epidemics in 1999–2005 (Figure 3). The phylogenetic tree was constructed by maximum parsimony analyses and rooted by using WN-NY99 and IS-98; it clearly shows that these 2 isolates were the predecessors of other US WNV isolates. Analysis of nucleotide sequence alignment of complete WNV genomes indicated that most mutations that occur each year were not fixed. However, WNV has continued to diverge and the total number of fixed mutations and the overall nucleotide divergence have increased. Some mutations in US isolates may have appeared as a result of native adaptation and genetic drift of parental WNV isolates (18).


Genetic variability of West Nile virus in US blood donors, 2002-2005.

Grinev A, Daniel S, Stramer S, Rossmann S, Caglioti S, Rios M - Emerging Infect. Dis. (2008)

Phylogenetic tree of complete genomes of West Nile virus (WNV) isolates collected during the 1999–2005 epidemics in the United States. Phylogeny reconstruction was estimated by using MEGA version 3.1 (www.megasoftware.com) on the basis of maximum parsimony analysis. Solid circles indicate isolates from this study. Values near branches represent percentage support by parsimony bootstrap analysis. Some parsimony-informative positions (1442, 2446, 4146, 6138, 6721, 8811, 10408, and 10851) play an important role in topologic arrangement of the tree and outgroup configurations. The tree was rooted with prototype WNV isolate WN-NY99 (AF196835) and the most closely related Old World isolate, IS-98 (AF481864). Culex q., Culex. quinquefasciatus; Culex t., Cx. tarsalis; Culex p., Cx. pipiens. WNV genotype is color coded: green, WN99; blue, WN02.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2570840&req=5

Figure 3: Phylogenetic tree of complete genomes of West Nile virus (WNV) isolates collected during the 1999–2005 epidemics in the United States. Phylogeny reconstruction was estimated by using MEGA version 3.1 (www.megasoftware.com) on the basis of maximum parsimony analysis. Solid circles indicate isolates from this study. Values near branches represent percentage support by parsimony bootstrap analysis. Some parsimony-informative positions (1442, 2446, 4146, 6138, 6721, 8811, 10408, and 10851) play an important role in topologic arrangement of the tree and outgroup configurations. The tree was rooted with prototype WNV isolate WN-NY99 (AF196835) and the most closely related Old World isolate, IS-98 (AF481864). Culex q., Culex. quinquefasciatus; Culex t., Cx. tarsalis; Culex p., Cx. pipiens. WNV genotype is color coded: green, WN99; blue, WN02.
Mentions: Phylogenetic analysis of complete genomes of WNV isolates provided stronger evidence of evolutionary relationships between isolates. Eight fully sequenced isolates were compared by phylogenetic analysis with 39 published complete WNV genomes present in the United States during epidemics in 1999–2005 (Figure 3). The phylogenetic tree was constructed by maximum parsimony analyses and rooted by using WN-NY99 and IS-98; it clearly shows that these 2 isolates were the predecessors of other US WNV isolates. Analysis of nucleotide sequence alignment of complete WNV genomes indicated that most mutations that occur each year were not fixed. However, WNV has continued to diverge and the total number of fixed mutations and the overall nucleotide divergence have increased. Some mutations in US isolates may have appeared as a result of native adaptation and genetic drift of parental WNV isolates (18).

Bottom Line: Complete genomic sequences of 8 isolates and structural gene sequences from 22 additional isolates were analyzed.We found some genetic diversity in isolates from different geographic regions and genetic divergence from reported sequences from epidemics in 1999-2001.Nucleotide divergence of structural genes showed a small increase from 2002 (0.18%) to 2005 (0.37%), suggesting absence of strong selective pressure and limited genetic evolution of WNV during that period.

View Article: PubMed Central - PubMed

Affiliation: Food and Drug Administration, Bethesda, Maryland, USA.

ABSTRACT
West Nile virus (WNV) was detected in the United States in 1999, has reoccurred every summer since, and has become endemic. Transfusion transmission was documented in 2002, and screening of blood donations for WNV began in 2003. We investigated genetic variation of WNV in human isolates obtained from specimens collected from 30 infected blood donors who tested positive for WNV RNA during 2002-2005. Complete genomic sequences of 8 isolates and structural gene sequences from 22 additional isolates were analyzed. We found some genetic diversity in isolates from different geographic regions and genetic divergence from reported sequences from epidemics in 1999-2001. Nucleotide divergence of structural genes showed a small increase from 2002 (0.18%) to 2005 (0.37%), suggesting absence of strong selective pressure and limited genetic evolution of WNV during that period. Nevertheless, WNV has continued to diverge from precursor isolates as geographic distribution of the virus has expanded.

Show MeSH
Related in: MedlinePlus